SFFS608 june 2023 TPS3435 , TPS3435-Q1 , TPS3436-Q1 , TPS35 , TPS35-Q1 , TPS36-Q1
4 Pin Failure Mode Analysis (Pin FMA)
This section provides a Failure Mode Analysis (FMA) for the pins of the TPS3435, TPS3436, TPS35, and TPS36. The failure modes covered in this document include the typical pin-by-pin failure scenarios:
- Pin short-circuited to Ground (see Table 4-2)
- Pin open-circuited (see Table 4-3)
- Pin short-circuited to an adjacent pin (see Table 4-3)
- Pin short-circuited to supply (see Table 4-5)
Table 4-2 through Table 4-5 also indicate how these pin conditions can affect the device as per the failure effects classification in Table 4-1.
| Class | Failure Effects |
|---|---|
| A | Potential device damage that affects functionality |
| B | No device damage, but loss of functionality |
| C | No device damage, but performance degradation |
| D | No device damage, no impact to functionality or performance |
Figure 4-1 and Figure 4-2 show the TPS3435, TPS3436, TPS35, and TPS36 pin diagrams. For a detailed description of the device pins please refer to TPS3435, TPS3436, TPS35, or TPS36 in the Pin Configuration and Functions section of the data sheet.
Figure 4-1 Pin Configuration Option CDDF Package,8-Pin SOT-23,
TPS35 and TPS36 Top View
Figure 4-2 Pin Configuration Option CDDF Package,8-Pin SOT-23,
TPS3435 and TPS3436 Top View
Following are the assumptions of use and the device configuration assumed for the pin FMA in this section:
- Output reset Pullup Resistor (RPULLUP) = 10 kΩ, Output reset pullup voltage (VPULLUP = 5.5 V, output reset load (CLOAD) = 10 pF.
- Tables valid over the operating free-air temperature range of – 40°C to 125°C, unless otherwise noted.
- Typical values are at TA = 25°C, VDD = 6.0 V unless stated otherwise.
| PIN NAME | PIN NO. | DESCRIPTION OF POTENTIAL FAILURE EFFECT(S) | FAILURE EFFECT CLASS |
|---|---|---|---|
| SET0 | 1 | Unexpected behavior if application needs SET0 = 1. | B |
MR | 2 | RESET/WDO is asserted. | B |
WDI | 3 | Constant WD timeout faults. | B |
GND | 4 | Expected operating condition. | D |
| SET1 | 5 | Unexpected behavior if application needs SET1 = 1. | B |
WD-EN | 6 | Leads to large indeterminate voltage levels. This causes large currents that can damage the device. The output behavior is not deterministic. | A |
| WDO / RESET(Open Drain) | 7 | WDO / RESET constantly asserted; some additional current can flow through pullup resistor. | B |
| WDO / RESET(Push Pull) | 7 | Functionality lost and can cause permanent damage. | A |
| VDD | 8 | Device non-operational. | B |
| PIN NAME | PIN NO. | DESCRIPTION OF POTENTIAL FAILURE EFFECT(S) | FAILURE EFFECT CLASS |
|---|---|---|---|
| SET0 | 1 | Leads to large indeterminate voltage levels. This causes large currents that can damage the device. The output behavior is not deterministic. | A |
MR | 2 | Device can not pass MR to RESET. | B |
WDI | 3 | Nothing happens until error condition, then reset delay is 2 mS. | C |
GND | 4 | Device is non-operational. | B |
| SET1 | 5 | Leads to large indeterminate voltage levels. This causes large currents that can damage the device. The output behavior is not deterministic. | A |
WD-EN | 6 | Nothing happens until error condition or power cycle, then WD is disabled. | B |
| WDO / RESET(Open Drain) | 7 | Constant high, no WDO/RESET functionality. | B |
| WDO / RESET(Push Pull) | 7 | High impedance output, no WDO/RESET functionality. | B |
| VDD | 8 | Device is non-operational. | B |
| PIN NAME | PIN NO. | SHORTED TO | DESCRIPTION OF POTENTIAL FAILURE EFFECT(S) | FAILURE EFFECT CLASS |
|---|---|---|---|---|
| SET0 | 1 | MR | High current at a system level can flow to the device driving MR or SET0. | B |
MR | 2 | WDI | High current at a system level can flow to the device driving MR or WDI. | B |
WDI | 3 | GND | Constant WD timeout faults. | B |
GND | 4 | SET1 | Unexpected behavior if application needs SET1 = 1. | B |
| SET1 | 5 | WD-EN | SET1 toggles with WD-EN. | B |
WD-EN | 6 | WDO / RESET(Open Drain) | High current can flow from WD-EN or WDO / RESET based on the pullup resistor value. | B |
WD-EN | 6 | WDO / RESET(Push Pull) | Can cause permanent damage. | A |
| WDO / RESET(Open Drain) | 7 | VDD | Large current can flow into WDO/RESET when in error condition. This can cause permanant damage. | A |
| WDO / RESET(Push Pull) | 7 | VDD | Can cause permanent damage. | A |
VDD | 8 | SET0 | Unexpected behavior if application needs SET0 = 0. | B |
| PIN NAME | PIN NO. | DESCRIPTION OF POTENTIAL FAILURE EFFECT(S) | FAILURE EFFECT CLASS |
|---|---|---|---|
| SET0 | 1 | Unexpected behavior if application needs SET0 = 0. | B |
MR | 2 | High current can flow into the device driving MR. | B |
WDI | 3 | Constant WD timeout faults. | B |
GND | 4 | Device is non-operational. | B |
| SET1 | 5 | Unexpected behavior if application needs SET1 = 0. | B |
WD-EN | 6 | Watchdog is always enabled, loss of WD-disable functionality. | B |
| WDO / RESET(Open Drain) | 7 | Large current can flow into WDO/RESET when in error condition. This can cause permanant damage. | A |
| WDO / RESET(Push Pull) | 7 | Can cause permanent damage. | A |
| VDD | 8 | Normal operation. | D |